The present invention relates to a scroll fluid machine and especially relates to a scroll fluid machine such as a scroll vacuum pump, a scroll compressor, a scroll expander or a scroll blower, in which a fixed wrap of a fixed scroll in a housing is engaged with an orbiting wrap of an orbiting scroll rotatably mounted to an eccentric portion of a driving shaft, the orbiting scroll being eccentrically revolved by the driving shaft so that a gas sucked through the circumference or center is pressurized or depressurized as it moves toward the center or circumference and discharged.
In the scroll fluid machine which is known among persons skilled in the art, an orbiting scroll rotatably mounted to an eccentric portion of a driving shaft has an orbiting end portion, and a fixed scroll has a fixed end portion. An orbiting wrap of the orbiting end portion is engaged with a fixed wrap of the fixed end portion to form a sealed chamber, and there is provided a self-rotation-preventing mechanism for the orbiting scroll.
By the eccentric portion and the self-rotation-preventing mechanism, the orbiting scroll is eccentrically revolved, and according to a direction of revolving, the volume of the sealed chamber is gradually decreased toward the center or increased toward the circumference, so that fluid sucked through the circumference is introduced to the center under pressurizing or fluid sucked through the center is discharged through the circumference under depressurizing.
In factories and various workshops, various kinds and capabilities of scroll fluid machines are placed depending on the contents of working. A plurality of different scroll fluid machines are usually disposed in relevant factories, taking account of the type and capability expected in use. However, it is not economical in fixing cost, occupation area, the rate of operation and maintenance.